--- title: "Microwave magnetron & high-voltage repair" description: "KitchenAid microwave magnetron and high-voltage repair — it runs, the plate turns, the light is on and the food stays cold." url: "https://kitchenaidmiami.support/services/microwave-magnetron-and-high-voltage-repair/" date_modified: "2026-08-23" Appliance type: "Microwaves" --- # KitchenAid microwave magnetron & high-voltage repair ### Two circuits, one appliance A microwave runs its light, its turntable and its fan on the same power as a lamp. The heating comes from somewhere else entirely: a transformer, a capacitor, a diode and a magnetron, operating at a voltage that has nothing in common with the rest of your kitchen. That separation is exactly why a machine that appears to work perfectly can heat nothing at all. ### What actually goes wrong - **The magnetron**, which is the part most often behind “runs but does not heat”. - **The high-voltage diode and capacitor**, which imitate the magnetron and cost less. - **The transformer**, or on the inverter machines the inverter board. - **The thermal cut-outs**, which stop the appliance rather than let it overheat. ### One safety line worth reading The capacitor inside a microwave holds a charge that can injure you after the appliance has been unplugged for a long time. Everything else on this site has a paragraph of things you can check yourself. This repair does not, deliberately. ### What it costs From $245, and the honest conversation about whether the appliance deserves it is part of the visit. The exact cost is confirmed after the on-site diagnostic. What this involves The high-voltage side discharged and tested safely Magnetron, diode, capacitor and inverter proved separately Repair costed honestly against the appliance Confirm the symptom is what it sounds like Turntable, light and fan run from ordinary household power; the heating comes from a separate high-voltage circuit. All of the first three can look perfectly normal with no heat at all, which is why "it runs but nothing heats" is such a specific complaint. Make it safe before anything else The capacitor inside holds a charge that can injure you long after the appliance has been unplugged. It is discharged properly as the first step of the job, every time. Test the circuit part by part Magnetron, high-voltage diode, capacitor, transformer — and on the inverter machines the inverter board instead. They fail in ways that imitate each other, so they are measured rather than replaced in turn. Say whether it is worth doing On a countertop machine this repair often costs more than the appliance is worth and we will tell you so. On a built-in or a hood combination, where replacement means matching a cabinet opening, the arithmetic usually goes the other way. Two circuits, one appliance A microwave runs its light, its turntable and its fan on the same power as a lamp. The heating comes from somewhere else entirely: a transformer, a capacitor, a diode and a magnetron, operating at a voltage that has nothing in common with the rest of your kitchen. That separation is exactly why a machine that appears to work perfectly can heat nothing at all. What actually goes wrong The magnetron, which is the part most often behind “runs but does not heat”. The high-voltage diode and capacitor, which imitate the magnetron and cost less. The transformer, or on the inverter machines the inverter board. The thermal cut-outs, which stop the appliance rather than let it overheat. One safety line worth reading The capacitor inside a microwave holds a charge that can injure you after the appliance has been unplugged for a long time. Everything else on this site has a paragraph of things you can check yourself. This repair does not, deliberately. What it costs From $245, and the honest conversation about whether the appliance deserves it is part of the visit. The exact cost is confirmed after the on-site diagnostic. ### It runs but nothing heats up. That is the classic high-voltage failure. Everything you can see — the light, the turntable, the fan — runs on ordinary household power, so a machine can look completely healthy and produce no heat at all. It is not an owner repair: there is a capacitor inside that holds a dangerous charge after the appliance is unplugged. ### Can I open it up and look? Please do not. This is the one appliance on this site where we do not publish a "here is what to check first" list, and the reason is that capacitor. Unplug it, stop using it, and book the visit. ### Is a countertop model worth repairing? Often not, and we will say so rather than take the job. A built-in unit or a microwave-hood combination is a different question entirely, because the appliance is fitted to an opening and replacing it can mean cabinetry work. ### What does the repair cost? From $245, depending on which part of the high-voltage circuit has gone and whether the machine is an inverter model. The exact cost is confirmed after the on-site diagnostic and agreed with you before anything is ordered — including the conversation about whether to do it at all. --- **[Read full article: Microwave magnetron & high-voltage repair](https://kitchenaidmiami.support/services/microwave-magnetron-and-high-voltage-repair/)**